Hair conditioning formulations based on liquid ester quats and/or imidazolinium salts are characterized by excellent conditioning properties and ease of use and versatility. However, the long-term stability of simple formulations compared to solid ester quats and/or imidazolinium salts is lacking. Emulsion stabilization is problematic.
U.S. Pat. No. 6,376,455 discloses in example 7 a formulation comprising hydroxyethylcellulose and a quaternized esterification product of methylethylisopropanolamine. Reproductions reveal that the ester quat used has a melting point of at least 85° C. at 1 bar.